1. Field of the Invention
The present invention pertains to cyclones for separating fluids into components of different weights or densities. A typical cyclone comprises a housing, the major portion of which is conical. The housing may also include cylindrical portions adjoining the opposite ends of the conical portion. The fluid to be separated may, for example, comprise a liquid having a slurry of solid particles suspended therein. This fluid is injected into a blind annular space at the large diameter end of the cyclone housing by an inlet which directs the fluid tangentially against the inner wall of the housing. The fluid thus begins to flow along the inner wall in a path spiraling away from the large end. The reduction in diameter along the conical section of the housing wall causes angular acceleration of the flowing fluid. The heavier constituents settle radially outwardly toward the wall under centrifugal force and continue spiraling along the wall, while the lighter constituents reverse axial direction and flow upwardly and are removed through an outlet located centrally in the large end of the housing. The heavy constituents are removed through a second outlet at the small end. Thus the fluid is separated into two components. One component may be primarily liquid and the other primarily solid particles, for example, or one component may consist of liquid containing relatively small suspended particles and the other component of liquid containing larger particles. One or both components may be directed into another cyclone or other separating device for further separation of constituents.
As mentioned above, the fluids handled by cyclones often contain solid particles, and these particles are often of an abrasive nature. Abrasion by the particles is increased by the high angular velocities at which they move along the sides of the cyclone housing. As the angular velocity and gravitational forces increase toward the small end of the cyclone, the abrasive wear effect becomes more pronounced, reaching a peak near the small end (solids) outlet. To protect the relatively expensive housing from such abrasion, a liner, whose configuration generally parallels that of the housing, is often disposed therein. When the liner becomes worn, it can be removed and replaced more easily and economically than could the cyclone housing.
Removable liners of one piece construction which cover the entire side wall of the housing, while substantially reducing the expense of housing repair or replacement, still involve waste in that their smaller diameter portions may become badly worn while the larger portions near the inlet are still in acceptable condition. This is due to the high velocities and gravitational forces adjacent the walls of the smaller diameter portions.
2. Description of the Prior Art
Various liner systems have been devised in an effort to provide a separate liner part for the smaller diameter portion of a cyclone housing. However, there has been great difficulty in designing such a system having simple but effective means for retaining the small liner part properly in place in the cyclone.
U.S. Pat. Nos. 3,136,723 to Erwin et al and 3,057,476 to Gilbert each disclose liners having large and small diameter parts in axial or endwise abutment. In each case precision fits are required between the various parts of the liner and housing to prevent leakage, interference with proper flow, and other problems. Such precision fits are expensive, as they require such procedures as machining of the housing, and are sometimes virtually impossible to provide.
U.S. Pat. Nos. 2,622,735 to Criner and 3,902,601 to Townley each disclose a generally conical cyclone shell having an apex lining part disposed in its smaller diameter portion. In each case, the small lining part is prevented from upward movement, i.e., toward the large end of the shell, by a shoulder in the shell which abuts the upper and large end of the small lining part. However, movement in the opposite direction is prevented only by means disposed adjacent the small end or lower end of the small lining part. This is a distinct disadvantage, particularly if the lining part is formed of a relatively soft or flexible material, since its large or upper end can move about independently of the lower end causing an interruption in the desired smooth configuration of the surface over which the fluid will flow. Another disadvantage of the means for preventing downward movement of the small lining part in the Criner and Townley patents is that in each case this means includes at least one part separate from the lining and shell which serves as a retainer and which is removed when changing the small lining part.